Process of and apparatus for milling flour



Dec. 9, 1930. l. E. SMITH PROCESS OF' AND APPARATUS FOR MILLING FLOUR Filed Maron 29, 1950 von. l uw;

are generally Patented Dec. 9, 1930 LOUIS E. SMITH; OFMINNEAJPOLIS,

MINNESOTA,'ASSIGNOR, BY MESNE ASSIGNMENTS;

T0 HART-CARTER COMPANY, OF PEORIA, ILLINOIS, A CORPORATION OF DELAWARE PROCESS OF AND APPARATUS FOR MILLING .FLOUR `Application led March 29,

My invention provides an improved procy ess and apparatus for the milling of Hour and has for its object a simpler and more economical means `than hitherto employed and whereby there is obtained a greater percentage of high-grade Hour, a more complete and perfect separation of t-he bran from both high and low-grade iour, and improvements lin the several grades of flour. Generally stated, the invention consists of the novel steps of manipulation and novel combinations of vole-v vices hereinafter described and defined in the claims. For the purposes of this case, the grain reduced to iour will be assumed to be Wheat, although the process and apparatus may be used in the production of flour from other small grains and from corn. As is Well known, the `most difficult operation in the manufacture of flour is the complete separa-4 tion of the fine bran particles from the endo'- sperm or flour-producing substances of the,- Whole Wheat.

In the milling-process nowin general use, the Whole Wheat is irst broken into what is known as;chops, by break rolls and thereafter the separation of the bran and the germ from the endosperm is accomplished by combined crushing and grinding actions alter nated with sifting or separating actions.l The combined grinding and crushing actions produced by diferentially driven rolls, that is, rolls, one of which is driven at a higher peripheral speed than the other so that there Will be a grinding action produced simultaneously With the crushing action of the rolls.

The grinding action accompanying the crushing action has hitherto been considered as a necessityin order to break up the endosperm and separate the same from the bran, although it has been recognized that the grinding action produced by the differential movement of the rolls very greatly tends to break up'the bran into small particles, some of which cannot thereafter be completely separated from the flour. Hence in timing the differential actions of the roll, it has been necessary to make a compromise between extreme differential action desirable/ for high capacity grinding and a minimum of dier- 1930. Serial N0. 439,959.

ential desirable for crushing action. Another reason for the differential timing of the rolls has been found in the fact that crushing pres-V sure of the rolls tends to form flour flakes which have ,been difficult to bran Hakes and which have required further disintegration by grinding and siftingl actions so that in practice the operation ofthe repeated combined pressure grinding and separating actions have/necessarily been carried out to a very great-length. Moreover,l under the above old operation and process, the

repeated grinding actions necessary to reduce the flour Hakes results in reducing a considerable part of the ban to such fine condition that much thereof eventually finds its Way into the various flour streams.

.My invention results from the discovery or determination that a direct and simple crushing action such as produced from co-operating rolls driven at the same or nearly the same peripheral speed will crush or break down the endosperm with a `minimum of separate from the y grinding or breaking up of the bran or hull and incidentall of flour flakes, li thereafter with jecting the middlings or stock to a repetition of compressional impacts or reducing actions, such as produced by subjecting the stock to a free tumbling action in acontainer while commingled with loose impact-producing objects such as iron balls or particles.

A substantially horizontal rotary drum containing iron balls or the like is Well adapted for the use just last indicated, to wit: a reductionofthe flour flakesand separation ofthe endosperm from adhering bran lakes. The action of`- such a reducing device differs materially from thatv of the differentially driven rolls, millstones, and the like, for in such devices the, co-operating, grinding ele- -ments'have definite-fixed relation and vmove in definite pat-hs' so that any grain particle too langev to pass freely between the same must necessarily be cracked andreduced and the tumbling mill used in this' improved tend to press together bran Hakes and Hour process, the lls or reducing elements have no definite. paths of, movement and no deH- nite reducing actions, but Hoat about producing impacts under yielding movements. 0th'- -erwse stated, the balls or reducingelements.' in the tumbling mill in acting, orinstance,

upon a large bran Hake to which a considerable amount of endosperm is adhering, do not reduce-the endosperm by a single impact, but by repeated impacts so that the Hour Hakes and' endosperm are reduced and later sepaf ratedfrom the bran progressively and without toany considerable extent breaking up the bran. Hakes .f` vAlso co-operating rollers Hakesand to cause them to adhesively couple up as bran Hakes with adhering endosperm Hakes, whereas the action of the balls of the tumbling mill have no tendency to cause the bran Hakes to adhere to theHour Hakes andV on the contrary act to cause and maintain a separation of the bran Hakes from the Hour substance and, ofcourse, as already described, reduces the Hour Hakes to Hour. When the endosperm is crushed or broken down by pressure rolls. or the like, aconsiderable part thereof is likely to be formed into Hakes but these.Hakes or anyv other crushedvportion of the endosperm have veryv much less cohesion than doesthe original oruncrushed endosperm, and hence such Hakes or crushed endosperm may bepreadily reduced to Hour by subjecting the same to a repetition of the shower of compressional impacts such as produced by the so-called tumbling mill containing reducing balls'or elements.

Also it has been found that the wheat germl which. like the endosperm, will be, to a considerable extent, formed into Hakes, will have greater cohesion in Hake form than will the Hour Hakes and hence under proper regulation of the operation of the tumbling mill,

the Hour Hakes will be reduced to Hour without reducing the bran and germ Hakes, there` by `making separat-ing ofthe germ as wejll as the bran from the Hour a comparatively easy matter.

Tests have also shown that the 'gluten and starch granulesof the Hour are, to'a considerable extent, broken down the 'severe and repeated grinding actions hitherto employed in milling operations, but thatthe gluten and the starch granules are not broken down or damaged by theimpact and rolling actions such as produced-im accordance with my improved process in the use of the sogluten and starchgranules in Hour is known to be detrimental to the Hour.

tem, the crushing devices, separating devices called tumblingmill. Breaking down of 4the and tumbling percussion devices are comblned 1n a novel and proper manner for car-v rying out the lmproved process and may be combined with other devices such as puri- Hers, sitters and bolters, all as will hereinafter more fully appear.

The invention is illustrated in the accompanying'drawings wherein like characters in dicate like parts throughout the several views. Referring to the drawings;

Fig. 1 `is a diagrammatic How sheet illustrating the process and various instrumen-v talities or devices used in carrying the same into. eifect and Fig. 2 is a vertlcal section taken axially through one ofthe so-called ball or tumbling mills diagrammatically shown in Fig. 1.

- Referring to the diagrammatic view Fig. 1, the 'numeral 1 indicates a pair of first break rolls driven in the direction ofthe-arrows marked thereon and mounted in the usual or any suitable way.' By the rolls 1, the wheat is first broken 4into what is known as chops.

sav

From the first break rolls, the chops7 asV i indicated by a flow line 2 will be conveyed to a bolter or siftingmachine having a plurality of screens or sieves of which three are indicated by the numerals 3, 4; andi5, and the dimensions of which are progressively smaller from the upper to the lower member. Inp`ractice, of course, these screens or sieves will be vibrated a's in ordinary 'Hour mills.

Bran with endosperm attached usually desig.

from the upper sieve or screen 3 as indicated by a How line'6. Particles of endosperm and germ of about the same size mixed with lnated as first scalpings, will be scalped off willpass through screen 5 as indicated by .How line. 5. In the bolter that involves the screens 3, 4 and' 5, some .further or minor .separations'ma be performed but for the purpose .of lthis case, such may be here ignored.

rl`he middling's travelas indicated by How line 8 and are delivered to co-operating crushingrolls 9, hereindesignated as first mid- -l These rolls will be driven, in thedirection of the arrows marked thereon.4

dlings rolls.

inthe usual or any suitable waybut at the same or nearly the same peripheral speed or at any rate, at such slight speed differential a's will not disintegrate the bran to any ap preciableextent. In the How line 8, an ordi! nary purifier 10 such as 'generally used in Hour mills may be arranged for the-passage. of? the -middlings therethrough and the 'separation therefrom of light bran particles.

horizontal rotary drum 12 containing iron or metal balls 13 or the vlike arranged to freely roll about within said drum under rotation of the latter. The middlings passed through the drum 12 will be rolled about while comming'led with' the balls 1,3 and the middlings and the balls will be continuously raised and caused to roll or fall back in a continuous shower so that the middlings will. as already indicated, be subjected to a mild but continuous reducing action, herein designated as a shower of compressional impacts. This so-called shower ofr compressional impacts of continuous and repeatedmild re ducing actions, loosens theendosperm from the branparticles and reduces the endosperm to flour without, to any considerable extent, breaking up or disintegrating the bran particles. The flour Hakes produced by the rolls 9 will, of cour-se, by this action bebroken up and reduced to vflour form and as there is no intense compression produced between the flour or flour fiakes andbran flakes, no cohesion between the Hour and the bran flakes is produced. In some instances, a sieve or separating means may be interposed in the flow line 11 between the rolls 9 and drum 12 for taking ofi" some flour. The rotary drum 12 with its reducing balls or elements 13 are sometimes designated as tumbling mills and Vsometimes asball mills and which have heretofore been extensively used for reducingl cement, but should be of the type to 'permit the continuous flow of middlings therethrough.` Said mill may, for example, b c of the type illustrated in Fig. 2, which is a vertical axial section through the mill and will be hereinafter described more in detail.

From the drum 12 of the first ball mil-l, the m'iddlings are'l delivered as indicated by flow line 14 to a bolter or sitter havingone or more sieves or screens, the same in the present instance being illustrated as having two sieves 15 and 16. As indicated by iiow line 17, scalpings for further reduction are scalped off from the upper screen 15, fiour is siftedthrough the lower screen 16, as indiy cated by fiow line 1S, and the middlings, as

indicated by fiow line 19 are delivered to crushing rolls 20 of the same 'general character as the rolls 9. A purifier 21 mav be interposed in the flow line 19. By the rolls 20, the unreduced portions ot the endosperm are further crushed and reduced without to any considerable extent breaking up the bran flakes and from said rolls, the stoc-k is delivered vto a second tumbling mill or ball mill of the same character as the first noted mill 12-13 and of the same character as the said mill illustrated more in detail in Fig. 2, By the action of this tumbling mill, the endosperm is further loosened from the bran flakes and reduced to flour 'orlnand flour flakesproduced by the roll20 will also be disintegrated and reduced to Hour form. As

. indicated by flow line 22, the further reduced middlings will be delivered tov a third separator such as a bolter, which, as shown, has two sieves 23 and 24. Scalpings for further reduction will be scalped off from the upper screen 23, see flow line 23a; Hour will be sifted through the lower sieve 24, as indicated by flow line 25; andthe unreduced middlings, if any, with attached or commingled fine bran particles will be scalped off from the sieve 24, as indicated by the flow line 26 and the actions above described may be repeated until the lreduction of the endosperm to flour has been completed. i

T he first scalpings, as indicatedby fiow line 6, are delivered to second break rolls 27.n These second break rolls in their structure and operation are much like the first break rolls 1. but preferably have corrugations that are finer than those provided on the first break rolls. The first scalpings consist largely of broken wheat particles and bran with endosperm attached and by the action of the second break rolls 27, the endosperm will be crushed and loosened. From the second break rolls 27` as indicated by flow line 28` I the stock is delivered to a bolter which as illustrated, has three sieves or screens '29, 30, and 31.v .As indicated by flow line 32, scalp' ings are scalped ofi" from to third break rolls for continued reduction. The sizings passed. through upper lscreen 29 will be scalped ofi from the screen 30, as indicated Vby fio'w line 33, the flour will be sifted through the lower screen 31, as indicated by How line 34a, and the middlings will 2 be scalped ofi"- from the lower screen 31, as

the upper screen 29 j -and mav be delivered for further reduction indicated by fiow line 34. The middlings will be` delivered between second middling rolls 35, which.. in their construction and operation, are like or substantially like the rolls 9. A. purifier 3 6 may be interposed in How line 34. From the second middlings rolls 35, the

stock goes, as indicated by flow line 37, to a ball or tumbling mill of the character already described and which consists .of a rotary drum 12 containing reducing balls 13. I By the action of this mill and with an action already more fully described, .the endosperm is reduced to or towardfiour form without breaking up the bran and the flour flakes formed by rollers 35 will be disintegrated and reduced to fioul'. From drum l12, the stock goes as indicated by How line 38 to a bolter which, as shown, has sieves 39 and 40. Scalpings forl furtherreduction are scalped olf from upper sieve 39 as indicated by How;

line 41;,.Hour is sifted through lower sieve 4`0,` as\ indicated by How line 42; and the middlings as indicated by How line 43 is de- 44 are reduced to Hour without breaking up the bran flakes. From this lastdrum 12,

the middlings go, as indicated byflow line 46, to another bolter which, as shown, has sieves 47 and 48.` Scalpings for further reduction are scalped off` from the upper screen 47, as indicated by How line 49; Hour goes through lower sieve 48, as indicated by How line 50; andthe middlings for further reduction are scalped off from sieve 48, as inv dicated by How line 51. Insome instances, it

may be desirable to interpose sifting or separating devices for drawing off Hour at one or more points such, for example, as between rolls 9 and drum 12 and rolls 44 and drum 12, rolls 20 and drum 12 and rolls 52 and drum 12, and between rolls 3 5 and drum 12'.

The sizings as indicated by'flow line 7, go to compression rolls herein designated as sizings rolls 52 and are constructed and operate substantially the same as rolls 9 and 35. If desired, a purifier 53 can be interposed in flow line 7. By rolls 52 the, endosperm will be, crushed and separated or loosened' from the bran particles and Hour Hakes will be produced by the compressingaction of the rolls but` the bran particles will not be disintegrated -or broken up to any considerable extent. Also the germ particles will be formed into Hakes.

In the specification, the term bolter is used in a broad. sense to include any and all kinds of suitable Hour-sifting devices.

This stock consisting of some Hour, Hour flakes, germ Hakesand bran flakes go to a ball or tumbling mill which, like the tumbling mills previously described, comprises aA rotary drum 12 containing reducingballs 13.

'By the action of this mill, the endosperm and Ho ur Hakes will be reduced to Hour form without reducing or disintegrating the germ Hakes and without breaking up the bran Hakes. The stock then goes to a bolter as indicated by the How line 54 which, as shown, comprises-sieves 55 and 56. The bran particles and the germ flakes will be scalped off from its upper screen 55 as indicated by flow line 57; the Hour will pass through lower sieve 56, as indicated by How line 58 andthe middlings, as indicated.

by flow line 59, will be scalped off lfrom screen 56 for further reduction.

I have found that in practice the above described action of the ball or tumbling mill,

in addition to the functions already discussed in detail, improves the quality ofthe Hour and hence, in some instances, it may be' de-` sirable to pass the Hour as frequently as possible through these impact-producing devices or mills. This could -be accomplished in many ways but the following will illustrate: -v

The Hour from How. line 34 by a deHector or guiding means 60 could be directed as by a How` line 61 into vthe first miIl'12I-13;V and the Hour from How line 42 by a deHector or guiding means 62 might be directed by a How line 63 into the second ball or .tumbling mill.

The ball mill shown in Fig. 2 is ltypical of all of the ball or tumbling mills illustrated in the diagrammatic-How sheet but may be assumed to be the first described ball mill for A ply spout 11a has a sleeve extended through the' large trunnion of the drum 12 and working therein is a spiral conveyor 11b. This arrangement, of course, permits a continuous flow of stock through the drum. Thehead l2b of said .drum is provided with a trunnion 12c journaled in a bearing 12c1 and said trunnion is shown as provided with a pulley 12Bl by means of which the drum may be rotated.

This system is adapted. to be used in a Hour mill on so-called sizings, middlings or tailings stock. This stock is produced ,from so-called chops or parts thereof after grinding. Various streams of middlings and sizings are then subjected to sifting or sifting and aspiration. then delivered tothe so-called sizings or middlings rolls and after this process and the possible removal of some Hour, the stock is then to be delivered to tumbling drums, after which it is subjected to further sifting or sifting and aspira-tion, where some Hour is taken out and the remainder carried again to further reduction along the lines mentioned above.

What I claim is:

1. The process of milling flour which consists in subjecting the whole grain to a crushing compression to crack the bran and break ifa down the endosperm, some of which endosperm is pressed into the form of Hakes, in repeatedly subjecting the middlings'portion of the .resulting stockfto a `multiplicity of non-uniform compressional impacts where\ by the endosperm and Hakes thereof are fur- '.ther reduced to or toward flour form without lCO materially disintegrating the bran Hakes, and in separating the bran from the flour.

2. The process of milling flour which consists in subjecting the whole grain to a crushing compression to crack the bran and break down the endosperm, in separating a portion of the bran and a portion of the fiour to isolate the middlings, in repeatedly subjecting the middlings to a multiplicity of uncontrolled compressional impacts whereby the endosperm and flakes thereof are further reduced to or toward flour form without materially disintegrating the bran flakes, and in separating the bran from the flour.

8. The process of milling flour' which consists in subjecting the whole grain to a crushing compression to crack the bran and break down the endosperm, in separating a portion ol2 the bran and a portion of the flour to isolate the middlings, in subjecting the'middlings to a further crushing compression thereafter repeatedly subjecting the middlings to multi-directional and uncontrolled impacts, whereby-theendosperm and iakes thereoi are further reduced to or toward tlour torm without materially disintegrating the bran iiakes, and in separating the flour from the bran and other particles not reduced to hour.

The process ot milling deur which consists in subjecting the whole grain to a crushing compression to crack the bran and break down the endosperm, in separatinga portion et' the bran and a portion of the ilour to isolate the middlings, in subjecting the middlings to a further thereafter repeatedly subjecting the middlings to a multiplicity of uncontrolled compressional impacts whereby the endosperm and :tlakes thereof are further reduced to or toward flour form without materially disintegrating the bran flakes, in separating the flour from the bran and other particles not reduced to our, in again subjecting the midu dlingsv to a crushing compression action, and

in again repeatedly subjecting the lour-producing stock to amultiplicity of uncontrolled compressional impacts and thereafter separating the flour from the bran particles and other particles not reduced to flour.

5. rihe process of milling iiour which cona sists in subjectingthe whole grain to a crushing compression to crack the bran and break dawn the endosperm, in separating'the'stock inte at least three streams, to wit: middlings, scalpings and siZingS, in subjecting -thermiddlings to a -t'urther crushing com pression, then te a multiplicity of uncnntrailed compressional impacts and then to a tiour sitting action; in subjecting the scalpings to a further crushing compression, `then to a. tlour separating action, then to a further crushing compression, then to a multiplicity ont uncontrolled compressional impacts and then to a tlour separating action; and in subj bran is removed crushing compression,A

jecting the sizings to a further crushing coml pression, then to a multiplicity of uncontrolled compressional impacts and then toa pacts and then to further flour separatingaction.

7. 'llhe process deined in claim 5in which both the middlings andthe flour-producing stock from the scalpings are subjected to further crushing compressions, then to a further multiplicity 'of uncontrolled compressional impacts, and then to further Hour separating actions.

8. The process of milling flour which consists insubjecting thewhole grain'to a crushing compression to crack and loosen the bran or hull, in subjecting the cracked grainnto a separating action whereby a portion. oit the subjecting the middlings to a crushing comfpression to further reduce the-same to deur, some ont which will be pressed into the form. of Hour flakes, in subjecting stock thus treated to a multiplicity ot' uncontrolled. compressional impacts to disintegrate the Hour flakes and further reduce the tiour middlings, .and in subjecting the stock thus treated to a second separating action to separate the loose flour from the minor bran akes and remain ing coarse portions.

9. rlhe process of milling iieur which conn sists in subjecting the whole grain te a crushu ing compression to crack and loosen the bran or hull,'in subjecting the cracked grain to separating action whereby a portion of the bran is removed to isolate the middlings, in

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to isolate the middlings, in ,i

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subjecting the middlings to a turthercrush bran Hakes and remaining Hour Hakes, in

subjecting the undisintegrated lour parti cles and .minor bran flakes to a third crushing compression to thereby further reduce the tiour-torming particles, in tumblingand at the same time subjecting stock thus treated to the action or" a second shower of compressional impacts to further disintegrate the Hour flakes and endosperm, and in subjecting stock thus treated to a third separating action whereby` the flour is separated from the minor bran particles and other particles not reduced to deur.

l0. A Hour milling system comprisingl rae means for subjecting whole wheat to a crus ing compression to crackvthe bran and break down the endosperm and to press some of theendosperm into flake form, means for subjecting a portion of the resulting stock to a multipliclty of non-uniform compressional impacts whereby the endosperm and bers whereby the endosperm and to crack the bran and break down the endosperm and to press some of the endosperm into flake form, a tumbling mill including a rota drum and loose reducing elements therein, arranged to receive a portion of the resulting stock and to' subject the same to a shower of multi-directional movable mem- Hakes thereof are further reduced to or toward iiour form without materially disintegrating the'bran flakes, and separating means for separating the flour from the branand other particles .not reduced to the form of flour, combinedl with means for delivering the stock from the one to the other of said means. 12. A flour milling system 'comprising crushing rolls operative on the whole grain with a crushing compression to crackand break down the endosperm, separating sieves for separating the middlings from the scalp.- 'ings and sizings, other crushing rolls oper.-

ative on the middlings to further crush and compre/ss the same, and means thereafter operatve on the middlings to commingle the same with freely movable impacting'bodies whereby` the endosperm and flakes thereof are further reduced to or toward lourform without materially disintegrating the bran flakes, and additional separating means for j subsequently separating the flour from the bran and other particles not reduced to the form of flour, combined with means for delivering the stock from the one to the other of said means.

13. The structure defined in claim 12 in further combination with additional c rushing and compressing rolls further operative on the flour-producing stock, additional means forneXt subjecting the flour-producing stock to a shower of uncontrolled vloose members whereby the endosperm and flakes thereof are further reduced to or toward ilour form without materially disintegrating the branflakes, and further separating means subsequently operative on the flour-producing stock to separate the flour from the bran and other particles not reduced to flour.

14;. A flour milling system comprising lmeans for subjecting the. whole grain to a `crushing compression to crack the bran and break down the endosperm, separating means operative to separate the stock thus compressed and cracked into three streams, to wit: middlings, scalpings and sizings, means for subjecting the middlings to a Afurther crushing compression, then to multidirectional moving compressional members and then to a flour sifting action j vmeans for subjecting the scalpings to a furthercrushing compression, then to a flour sifting action, then to a further crushing compression, then; to multi-directionaly moving compressional members, and then to aflour-separatingaction; and means for subjecting the sizings to a further crushing compression, then to multi-directional moving compressional members and then to a flour-separating action.

15.. The structure definedin claim 14 in" further combination with means for subjecting the middlings to a further crushing compression, then to multi-directional lmoving compressional'members and then to further flour-separating action.

16. -A flour milling system comprising means for subjecting the Whole grain to a crushing compression to crack the bran and break down the endosperm, separating means operative to separate the stock thus compressed and cracked into three streams,

to wit: middlings, scalpings and sizings,

means for subjecting'the middlings to a further crushing compression, then to a shower of non-uniform compressional impacts and then to a iour sifting action; means for subjecting the scalpings to a further crushing compression then toa flour sifting action, then to a furthercrushin compression, then to a shower of non-uni orm compressional impacts-and then to a flour-separating ac` tion; and means for subjectingthe sizings to a further crushin compression, then to a shower of non-uniform compressional impacts andthen-to a flour-separating action.

17. The structure defined in claim 16 in further combination with means for subjecting the middlings and the flour-producing stock from the scalpings to further crushing compressions, then to further showers of nonuniform compressional impacts'an-d then to further flour-separating actions.

18. The process of milling flour which consists in. subjecting the. whole graintoa crushing compression to crack the bran and break down "the endosperm, some of which endosperm is pressed into the form of flakes, and comminglinga portion of the resulting stock with freely movable impacting bodies, tumbling the aggregation to further reduce the endosperm and flakes to or toward flour form without materially disintegrating the bran, and in separating the bran from the `iiour. v v

19. The process of milling flour which consists in subjecting the whole grain to a crushing compression to crack the bran and break down the endosperm, some of which endosperm is pressed into the form of flakes, and simultaneously commingling a portion of the resulting stock With freely movable impacting bodies and cascading the aggregation to further reduce the endosperm andl flakes to or toward Hour vform Withoutinaterially disintegratng the bran, and in separating the `bran from the Hour.

' In testimony whereof I aix my signature.

LOUIS E. SMITH. 

